Study On Methanol Formation During Alkaline Pulping Process Of Wheat Straw

Methanol has been identified as the main alcohol pollutant among the VOCs emitted from the pulping process. Regression was used to predict the methanol formation during the pulping process as a function of pulping variables, kappa number and pulp yield. Methanol formation process during the pulping process of Soda-AQ method had also been studied.Under the designed conditions, the result showed that methanol formation during the alkaline pulping process was good linearly related to pulping process variables (alkali charge, heat-up time, the Max Temperature and cooking time) and kappa number when the kappa number changed between 14～23. And it showed significant power exponent relation with pulp yield. When the kappa number decreased with 3 units, methanol formation would increase with 1 kg·t-1 (odp).Mathematical models of the methanol formation during Soda-AQ pulping process were established. And the model checking showed that these models could be used for predicting the methanol formation during the pulping process of Soda-AQ method within the limit of experiment.The methanol formation process during the pulping process of Soda-AQ method showed that, methanol content increased with the raise of cooking time and cooking temperature, and the higher alkali charge used the more methanol generated. When the cooking temperature was lower than 80℃, the methanol formation increased slowly; while, when the cooking temperature was at the temperature of 80℃～155℃, the methanol formation increased rapidly. During the at-temperature period, inspite of the lower increase rate,more methanol still generated in this period.During the KP pupling process, methanol formation increased with the raise of alkali charge, sulfidity, the Max. Temperature and cooking time. Compared with KP pulping process, much more methanol generated from the Soda-AQ pulping process with the same kappa number, especially when the kappa number was much lower.